A single latch snap lock base for annular fluorescent lamps is disclosed in issued U.S. Pat. No. 4,002,394, which is assigned to the assignee of the present invention. Said prior art plastic base comprises two semicylindrical parts wherein a first part comprises a dowel and a latch pin extending from the interior thereof which mates with a second part having recesses for receiving the dowel and latch pin elements to secure the two parts in a fixed relationship. While a double latch pin construction for said base is said to be useful, it is said to increase the force necessary to attach the base halves together as well as make it more difficult to disassemble the base halves if repairs are to be made during lamp manufacture. A boss member is included in said prior art base construction which is formed in one of the mating parts for receiving lead-in wires extending from the assembled lamp and reinforcing means are provided on the interior of said mating parts in the form of semicircular discs orthogonal to the semicylindrical surfaces to help prevent flexure after the parts have been assembled together. Rotation of the assembled base about the annular lamp is limited by other leg elements which protrude inwardly from the semicylindrical outer wall in one of the mating parts to engage a metal tang or a glass nodule on the lamp glass envelope.
A number of significant problems have been experienced with said prior art base construction as the speed of lamp manufacture has increased as well as during subsequent lamp use. The torqueing forces normally encountered during lamp manufacture and assembly not only caused unlatching of the mating parts after assembly but produced mechanical failures when the single latch pin in the assembled base was forced against the channel into which the latch pin had been inserted. These normal torqueing forces during lamp manufacture further applied an excess torque load on the leg elements used to prevent base rotation after lamp assembly which also tended to force the base halves apart exposing the uninsulated lamp lead-in wires. Untapered conductive contact pins and openings in the prior art base construction also produced frequent misalignment or mis-feeding of lead-in wires which became even more severe as the speed of lamp manufacture increased.
It would be desirable to alleviate all of the foregoing problems with an improved lamp base construction which does not require a major design change and which is also less subject to mechanical failure during lamp manufacture. Likewise, it would be desirable in producing said benefits if the improved lamp construction resisted base unlatching during use to a greater degree in order to reduce any consequent exposure of the uninsulated lamp lead-in wires.